Fundamental Molecular Data to Support CARS (Coherent Anti Stokes Resonance Raman Spectrometry) Diagnostics of Temperature, Pressure, and Species Concentration.

摘要

The J-, and T-dependence of line broadening and line shifting coefficients are reported for the A-branch spectra of Carbon Monoxide and various hydrogen diatomics. Experimental studies verify our ability to predict, using an energy-gap rate law description of the relaxation matrix equation, the collisionally narrowed A branch of self-broadened Carbon Monoxide. Line shifting is determined experimentally and accounted for by semi-classical calculation. This calculation also is shown to be very accurate for self-broadening in Carbon Monoxide and is used to predict line broadening in CO:N2 from 295 to 1500K. The Q-branch line shape function for the hydrogen diatomics is studied for a range of collision partners and temperatures. In the low pressure, Dicke narrowed regime, the basic line shape function is understood; however, there is no reliable basis for prediction of the (in some cases complex) optical diffusion coefficient. In the pressure broadened regime, anomalous, asymmetric lineshapes are reported for the H2(D2): Air system. These are ascribed to inhomogeneous broadening associated with the speed dependence of dephasing cross-sections. This lineshape is shown to collisionally narrow and symmetrize with increasing H2(D2) concentration. The J-dependence of the line broadening for the hydrogen diatomics is described. (AW)